Cutter bar for coal-cutting machines and the like



April 29; 1930. w. c. BLACK CUTTER BAR FOR COAL CUTTING MACHINES AND THE LIKE Filed Aug. 25, 1927 I'Y VEN TOE. M 14M W 6 81 4:4

Patent d Apr. 29, 1930 un -TED. STATES PATENT; :10 1

WILLIAM CHRISTIE BLACK, or DUDLEIIENGLAND, nssrenort 'ro' MATTHEW SMITH MOORE, or BRUSSELS, BELGIUM CUTTER BAR on coaracnr'rme MACHINES AND-THE m Application am August 25, 1927, SerialNo.215,'397, and in al iu'm Se ptember 13, 1926.-

' I This invention relates to cutter bars for coal cutting machines and the like,-and it hasfor its object to provide a bar that will have greater strength .than the cutter bars of cur- 5 rent design, in addition t0 be'ing more cheaply.

' manufactured and proving more reliable in retaining the picks for cutting the coal'or other minerals. I

.-In the usual coal cutting'machines of the 10 bar type the cutter bars are in the shapeo'f threaded rods having radial holes drilled therein and the cutter picks are provided with stems adapted to be inserted and keyed in po 'sition in said holes. It has also been proposed to out across the.thread a number of flat bottomed dovetailed slots for receiving cutter picks' having a fiat wedge-shap'ed'b'ase adapted to fit in such, slots. In structures of the first type the cutter picks-are-liable to 29 break at the junction of the stem with the outwardly projecting portion of the pick; moreover the'contacting surfaces'of the keys and keyways wear rapidly withlth'e result that the picks are liable to 'tur'n'in their seats. In structures of the second type referred to the slots or wedge-shaped seats for the cutter:-

1 ment the cutting edge may repeatedly be subjected to grinding before the pick has to-b'e discarded. It should also be mentioned that picks must be tangential to the bodyof the bar 1n order not unduly to weaken the same, with the result that the picks project radially '30 to a considerable distance and in use they makerln the coal or other material a cut of excessive thickness, Then also both structures require very costly machining, whether it be for drilling the holes and cuttingthe e5 keyw ys, or for. dressing the straight faces of theidovetailed slots. r

These various inconveniences are obviated by the present invention." To this end I also 'securejthe cutter picks in dovetailed slots in i difierent angles in order to produce the taper required to; retain the picks in position; the

.-machining ofthe bar'to provide the thread" and the slots therein can be completed in one "slots are formed by cutting. the thread at two setting on the lathe. By slightly. altering the longer andfirmer support of the cutter picks ls'aflorded than with a straight cut across the thread. -The slots .may 'beplace d very "close to each other, say at an'average distance equal to. the mean width of said slots. .In this case when a double threaded bar is used-the picks on -the two threads may be alternated so that they will cut the material along 'a practically continuous line, and reciprocating'motion of the bar may be dispensed with. This arrangement is suitablefor various applications other than coalwcutting, as for example for tree felling.

.The cutter picks with a curved base may.

be made by stamping at red'heat, and fini'shed on on the lathe if desired. The cutting r edge of each preferably projects forwardly of the base and ends in 'a' point the direction of which is' substantially tangential-to the underface of the .base. With this arrangem usethe' picks form on the cutter bar projection's of comparatively small size, whereby the thickness of the'cut and the attendant wasteis reduced. T I

The curved slot arrangement according "to the invention can also be used with advantage for securing-the cutter pick' usually-fitted at the outerend'of the cutter bar. In this case the botto m of the groove is .flat and its con-'. i .verg'ing side-walls are of arcu'ate shape, the

taper running in opposite direct-ionto the direction of rotation of-thebar.- I am thusenabled to' avoid the use of cotter pins and thedrilling of the bar which'impairs its ,re-

'sistancejand increases the cost of manufac-f ture.

. I Intheaccompanying drawings l have diagrammaticall illustrated, byway of example,-a cutter ar according to my invention.

a Fig. I is aside view of the barshowing the arrangement of the curved slots.

Figs. 2 and 3 show the outer end of the bar in axial section and end view respectively.

Figs. 4, 5 and 6 are respectively two side views and a top view of a cutter pick and Fig. 7 is a cross-section on line AB of Fig. 4.

Figs. 8 and 9 are a side view and a top view respectively of an end pick. Fig. 10 shows on a larger scale ment of the thread on the bar.

The bar 1 herein shown is provided with a right handed screw 2 through which are cut the dovetailed slots or seats 3 for the cutter picks 4. The thread being cut to the desired pitch by the'usual screw cutting means, the slots 3 are opened up by cutting to a shorter pitch, in direction of line a (Fig. 10) To obtain the necessary taper an additional cut is made in each slot in the direction of line b, at right angles to the axis of the bar, thus removing the metal over the shaded areas a. In each slot both side walls 5, 6 are undercut to give the desired dovetail grip. In Fig. 10 the distance (1 corresponds to the a developdevelopment of half the circumference of the I thread.

In these slots 3 are fitted the picks 4 (Figs. 4 to 7) with their curved bases having arcuate faces 7 8, 9 respectively corresponding to the bottom face and side faces 5 and 6 of the slots. .The side face 8 of each pick may extend over the whole depth thereof but the opposite face 9 preferably merges into a face 10 at right anglesto the axis of curvature of the other faces so as to strengthen the top portion 11 of the pick. The point 12 of the pick pro- .jects forwardly of the base and extends in. a

direction substantially tangential to the bottom face 7.

In the end face 13 of. the bar'is cut the curved slot 14 for accommodating the end pick 15. which, in the example illustrated, is provided with two points 16, 17. The side walls 18, 19of the base of this pick respectively correspond. to the undercut side walls 20, 21 of the slot 14:.

As shown in the drawing all the curved slots aretapered in opposite direction to'the direction of rotation of .the bar so that the grip on the cutter picks increases with the resistance to their rotation. Itwill also be seen that with their curved base the picks find in the slots :1 support of great length in. COIHPaIISOH to their size and more particular? ly in comparison to their radial dimensions, and that the construction described offers the various advantages above set forth. It will further be understood that the shape of the cutter bar and picks described with reference to the accompanying drawings may be varied without departing from the scope of this invention. r

Iclaim:

1. A cutter bar comprising a threaded rod having a dovetailed tapering slot cut through its thread, a wall of said slot being helical in shape.

2. A cutter bar comprising a threaded rod having dovetailed tapering slots cut through its thread, said slots having a longitudinally cylindrical bottom wall.

3. A cutter bar comprising a threaded rod having arcuate tapering slots cut through its thread, the bottom walls of said slots being concentric to the longitudinal axis of said rod.

4. A cutter bar comprising a threaded rod having dove-tailed tapering slots cut through its thread, one of the side walls of said slots being cut at right angles to the axis of the bar, the slots'having longitudinally cylindrical bottom walls.

5. A cutter bar comprising a threaded rod having an arcuate tapering slot cut across one of its end faces, said slot having its side wall undercut.

6. A cutter bar comprising a threaded rod having a tapering slot cut across one of its end faces said slot having a flat, arcuate bottom wall and longitudinally cylindrical side walls, the side walls being undercut.

7 A cutter bar comprising a threaded rod having an arcuate tapering slot cut through its thread, and an arcuate tapering slot cut across one of its end faces, the slot through the thread having a longitudinally cylindrical bottom wall, the slot across. an end face having undercut side walls.

' 8. A cutter pick comprising a tapered base having a longitudinally cylindrical bottom wall and side walls flaring outwardly and downwardly, and a top portion having a cutting point projecting in front of said base.

9. The combination of a cutter bar comprising a threaded rod having slots with longitudinally cylindrical bottom walls cut through its thread, and cutter picks having longitudinally cylindrical bases adapted to fit in said s10 10. A cutter barv comprising a threaded rod having tapering slots cut through its thread,

said slots having longitudinally cylindrical and transversely flat bottom walls, and underout side walls.

WILLIAM CHRISTIE BLACK. 

